Spin valve sensor having antiparallel (AP) pinned layer structure with low coercivity and high resistance

ABSTRACT

A spin valve sensor includes an antiparallel (AP) pinned layer that has first and second ferromagnetic layers separated by a thin coupling layer. The first ferromagnetic layer is exchange coupled to an antiferromagnetic pinning layer so that its magnetic moment is oriented in a first direction and the second ferromagnetic layer is exchange coupled to the first ferromagnetic layer with its magnetic moment oriented in a second direction that is antiparallel to the first direction. In the preferred embodiment the first ferromagnetic layer is cobalt iron niobium hafnium (CoFeNbHf) and the second ferromagnetic layer is cobalt (Co). With this arrangement the first ferromagnetic layer reduces current shunting and has a high coercivity so as to stabilize the pinning of the pinned layer. The cobalt (Co) of the second ferromagnetic layer enhances the spin valve effect by being adjacent to a nonmagnetic electrically conductive spacer layer which, in turn, is adjacent to a ferromagnetic free layer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a spin valve sensor with animproved antiparallel (AP) pinned layer and more particularly to an APpinned layer that has reduced current shunting and lower coercivity.

[0003] 2. Description of the Related Art

[0004] The heart of a computer is an assembly that is referred to as amagnetic disk drive. The magnetic disk drive includes a rotatingmagnetic disk, write and read heads that are suspended by a suspensionarm above the rotating disk and an actuator that swings the suspensionarm to place the read and write heads over selected circular tracks onthe rotating disk. The read and write heads are directly mounted on aslider that has an air bearing surface (ABS). The suspension arm biasesthe slider into contact with the surface of the disk when the disk isnot rotating but, when the disk rotates, air is swirled by the rotatingdisk adjacent the ABS to cause the slider to ride on an air bearing aslight distance from the surface of the rotating disk. When the sliderrides on the air bearing the write and read heads are employed forwriting magnetic impressions to and reading magnetic impressions fromthe rotating disk. The read and write heads are connected to processingcircuitry that operates according to a computer program to implement thewriting and reading functions.

[0005] The write head includes a coil layer embedded in first, secondand third insulation layers (insulation stack), the insulation stackbeing sandwiched between first and second pole piece layers. A gap isformed between the first and second pole piece layers by a gap layer atan air bearing surface (ABS) of the write head. The pole piece layersare connected at a back gap. Current conducted to the coil layer inducesa magnetic field across the gap between the pole pieces. This fieldfringes across the gap at the ABS for the purpose of writing theaforementioned magnetic impression in tracks on moving media, such as incircular tracks on the aforementioned rotating disk.

[0006] In recent read heads a spin valve sensor is employed for sensingmagnetic fields from the rotating magnetic disk. The sensor includes anonmagnetic conductive layer, hereinafter referred to as a spacer layer,sandwiched between first and second ferromagnetic layers, hereinafterreferred to as a pinned layer, and a free layer. First and second leadsare connected to the spin valve sensor for conducting a sense currenttherethrough. The magnetization of the pinned layer is pinnedperpendicular to an air bearing surface (ABS) of the head and themagnetic moment of the free layer is located parallel to the ABS butfree to rotate in response to external magnetic fields. Themagnetization of the pinned layer is typically pinned by exchangecoupling with an antiferromagnetic layer.

[0007] The thickness of the spacer layer is chosen to be less than themean free path of conduction electrons through the sensor. With thisarrangement, a portion of the conduction electrons is scattered by theinterfaces of the spacer layer with the pinned and free layers. When themagnetizations of the pinned and free layers are parallel with respectto one another, scattering is minimal and when the magnetizations of thepinned and free layers are antiparallel, scattering is maximized.Changes in scattering alter the resistance of the spin valve sensor inproportion to cos θ, where θ is the angle between the magnetizations ofthe pinned and free layers. In a read mode the resistance of the spinvalve sensor changes proportionally to the magnitudes of the magneticfields from the rotating disk. When a sense current is conducted throughthe spin valve sensor, resistance changes cause potential changes thatare detected and processed as playback signals.

[0008] A spin valve sensor is characterized by a magnetoresistive (MR)coefficient that is substantially higher than the MR coefficient of ananisotropic magnetoresistive (AMR) sensor. For this reason a spin valvesensor is sometimes referred to as a giant magnetoresistive (GMR)sensor. When a spin valve sensor employs a single pinned layer it isreferred to as a simple spin valve. A spin valve is also know as a topor bottom spin valve depending upon whether the pinning layer is at thetop (formed after the free layer) or at the bottom (before the freelayer). A pinning layer in a bottom spin valve is typically made ofnickel oxide (NiO).

[0009] Another type of spin valve sensor is an antiparallel (AP) spinvalve sensor. The AP pinned spin valve sensor differs from the simplespin valve sensor, described above, in that the pinned layer of the APpinned spin valve sensor comprises multiple thin layers, which arecollectively referred to as an antiparallel (AP) pinned layer. The APpinned layer has a ruthenium (Ru) spacer layer sandwiched between firstand second ferromagnetic thin layers. The first ferromagnetic thin layerhas its magnetic moment oriented in a first direction by exchangecoupling to the antiferromagnetic pinning layer. The secondferromagnetic thin layer is immediately adjacent to the free layer andis antiparallel coupled to the first thin layer because of the minimalthickness (in the order of 8 Å) of the spacer layer between the firstand second ferromagnetic thin layers. The magnetic moment of the secondferromagnetic thin layer is oriented in a second direction that isantiparallel to the direction of the magnetic moment of the firstferromagnetic layer.

[0010] The AP pinned layer is preferred over the single layer pinnedlayer. The magnetic moments of the first and second layers of the APpinned layer subtractively combine to provide a net pinning moment ofthe AP pinned layer. The direction of the net moment is determined bythe thicker of the first and second thin layers. The thicknesses of thefirst and second thin layers are chosen to reduce the net moment. Areduced net moment equates to a reduced demagnetization (demag) fieldfrom the AP pinned layer. Since the antiferromagnetic exchange couplingis inversely proportional to the net pinning moment, this increasesexchange coupling between the first ferromagnetic film of the AP pinnedlayer and the pinning layer. The high exchange coupling promotes higherstability of the head. When the head encounters elevated thermalconditions caused by electrostatic discharge (ESD) from an object orperson, or by contacting an asperity on a magnetic disk, the blockingtemperature (temperature at which magnetic spins of the layer can beeasily moved by an applied magnetic field) of the antiferromagneticlayer can be exceeded, resulting in disorientation of its magneticspins. The magnetic moment of the pinned layer is then no longer pinnedin the desired direction. A reduced demag field also reduces the demagfield imposed on the free layer which promotes a symmetry of the readsignal. The AP pinned spin valve sensor is described in commonlyassigned U.S. Pat. No. 5,465,185 to Heim and Parkin which isincorporated by reference herein.

[0011] The first and second ferromagnetic layers of the AP pinned spinvalve sensor are typically made of cobalt (Co). Unfortunately, cobalthas high coercivity, high magnetostriction and low resistance. When thefirst and second ferromagnetic layers are formed they are sputtereddeposited in the presence of a magnetic field that is orientedperpendicular to the ABS which sets the easy axis (e.a.) of theferromagnetic films perpendicular to the ABS. During operation of thehead the AP pinned layer is subjected to extraneous magnetic fields thathave components parallel to the ABS, such as components of the writefield. These extraneous fields, combined with heating of the pinninglayer, can cause the pinning layer to lose its pinning strength(exchange coupling) and allow the magnetic moments of the ferromagneticlayers to switch from being perpendicular to the ABS to some otherdirection. If the coercivity of the ferromagnetic films is higher thanthe exchange field that urges the magnetic moments of the ferromagneticlayers back to their original positions the magnetic moments of theferromagnetic layers will remain in the wrong direction. This rendersthe read head inoperable.

[0012] Cobalt (Co) has a high negative magnetostriction. The negativesign determines the direction of any stress induced anisotropy. When amagnetic head is lapped, which is a grinding process, nonuniformcompressive stresses occur in the layers of the sensor. Because of themagnetostriction and the stresses the cobalt (Co) ferromagnetic filmsacquire a stress induced anisotropy that is parallel to the ABS. This isthe wrong direction. The stress induced anisotropy may rotate themagnetic moment of the first and second ferromagnetic layers of the APpinned layer to some extent from perpendicular to the ABS in spite ofthe exchange coupling field tending to maintain the perpendicularposition. This condition can cause read signal asymmetry.

[0013] The low resistance of the cobalt (Co) ferromagnetic films of theAP pinned layer causes a portion of the sense current to be shunted pastthe free and spacer layers. This causes a loss of read signal.

[0014] Efforts continue to increase the spin valve effect of GMR heads.An increase in the spin valve effect equates to higher bit density(bits/square inch of the rotating magnetic disk) read by the read head.Promoting read signal symmetry is also a consideration. This isaccomplished by reducing the magnetic influences on the free layer. Asearch still continues to lower the coercivity, substantially eliminatemagnetostriction and increase the resistance of some of the criticallayers of the spin valve sensor.

SUMMARY OF THE INVENTION

[0015] The present invention provides a material for the pinning layerthat has higher resistivity and lower coercivity than the cobalt (Co)material typically employed in the pinning layer. This material isselected from the group comprising cobalt iron niobium hafnium(CoFeNbHf), cobalt iron niobium (CoFeNb), cobalt iron hafnium (CoFeHf)and cobalt niobium hafnium (CoNbHf) wherein the preferred atomic weightpercentage of CoNbHf is 87/11/2. The preferred material is cobalt ironniobium hafnium (CoFeNbHf). While cobalt (Co) has a resistivity of 10-12ohms square, cobalt iron niobium hafnium (CoFeNbHf), has a resistivityof 110 ohms square. Further, while cobalt (Co) has a coercivity of50-200 Oe, cobalt iron niobium hafnium (CoFeNbHf) has a coercivity of5-10 Oe wherein the atomic weight percentages were 86.5/0.5/11/2.

[0016] As mentioned hereinabove, the AP pinned layer has first andsecond ferromagnetic layers separate by a very thin ruthenium (Ru)layer. The first ferromagnetic layer is exchange coupled to the pinninglayer with its magnetic moment oriented in a first direction and thesecond ferromagnetic layer is exchange coupled to the firstferromagnetic layer with its magnetic moment oriented in a seconddirection antiparallel to the first direction. In a preferred embodimentthe first ferromagnetic layer is cobalt iron niobium hafnium (CoFeNbHf)and the second ferromagnetic layer is cobalt (Co). With this arrangementthe first ferromagnetic layer will reduce current shunting and have alower coercivity to stabilize pinning of the pinned layer. Cobalt (Co)is a preferred material for the second ferromagnetic layer since itenhances the spin valve effect by being adjacent to the spacer layer. Insome arrangements, however, it may be desirable for the secondferromagnetic layer to be cobalt iron niobium hafnium (CoFeNbHf).

[0017] In still other embodiments of the invention one or both of thefirst and second ferromagnetic layers may have first and second filmswhere one of the films is cobalt (Co) and the other film is cobalt ironniobium hafnium (CoFeNbHf). The invention is applicable to top or bottomspin valve sensors. In a top spin valve sensor the pinned layer ispinned by a pinning layer at the top of the sensor (pinning layer iscloser to the write head than the pinned layer) and in a bottom spinvalve sensor the pinned layer is pinned by a pinning layer that is atthe bottom of the sensor pinning layer is (further away from the writehead than the pinned layer). In a bottom spin valve sensor nickel oxide(NiO) is typically employed for the pinning layer. In this type ofsensor a nickel iron (NiFe) interface layer is employed between thepinning layer and the pinned layer for the purpose of promoting exchangecoupling. Still further, in some embodiments of the invention a spinvalve enhancement layer is employed. The spin valve enhancement layer isa very thin layer of cobalt (Co), such as 10 Å, that is located betweenand interfaces each of the spacer layer and the pinned layer. Theinvention can also be employed for simple spin valve sensors where asingle pinned layer is employed.

[0018] An object of the present invention is to provide material for apinned layer for a spin valve sensor that has higher resistivity andlower coercivity than prior art materials employed for pinned layers.

[0019] Another object is to provide a spin valve sensor that hasimproved pinned layer stability in the presence of extraneous fields.

[0020] A further object is to provide an AP pinned spin valve sensorwherein a first ferromagnetic layer antiparallel coupled to the pinninglayer has high resistivity and low coercivity and a second ferromagneticlayer interfacing the spacer layer is cobalt (Co) for promoting a GMReffect.

[0021] Other objects and advantages of the invention will becomeapparent upon reading the following description taken together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a planar view of an exemplary magnetic disk drive;

[0023]FIG. 2 is an end view of a slider with a magnetic head of the diskdrive as seen in plane 2-2;

[0024]FIG. 3 is an elevation view of the magnetic disk drive whereinmultiple disks and magnetic heads are employed;

[0025]FIG. 4 is an isometric illustration of an exemplary suspensionsystem for supporting the slider and magnetic head;

[0026]FIG. 5 is an ABS view of the slider taken along plane 5-5 of FIG.2;

[0027]FIG. 6 is a partial view of the slider and magnetic head as seenin plane 6-6 of FIG. 2;

[0028]FIG. 7 is a partial ABS view of the slider taken along plane 7-7of FIG. 6 to show the read and write elements of the magnetic head;

[0029]FIG. 8 is a view taken along plane 8-8 of FIG. 6 with all materialabove the write coil and write coil leads removed;

[0030]FIG. 9 is an isometric ABS illustration of a read sensor whichemploys a spin valve sensor of the present invention;

[0031]FIG. 10 is an isometric ABS illustration of a first investigatedsimple spin valve sensor;

[0032]FIG. 11 is an isometric ABS illustration of the present simplespin valve sensor;

[0033]FIG. 12 is an isometric ABS illustration of a second investigatedAP pinned spin valve sensor;

[0034]FIG. 13 is an isometric ABS illustration of a first embodiment ofan AP pinned spin valve sensor of the present invention;

[0035]FIG. 14 is an isometric ABS illustration of a second embodiment ofthe present AP pinned spin valve sensor;

[0036]FIG. 15 is an isometric ABS illustration of a third embodiment ofthe present AP pinned spin valve sensor;

[0037]FIG. 16 is an isometric ABS illustration of a fourth embodiment ofthe present AP pinned spin valve sensor;

[0038]FIG. 17 is an isometric ABS illustration of a fifth embodiment ofthe present AP pinned spin valve sensor;

[0039]FIG. 18 is an isometric ABS illustration of a sixth embodiment ofthe present AP pinned spin valve sensor;

[0040]FIG. 19 is an isometric ABS illustration of a seventh embodimentof the present AP pinned spin valve sensor; and

[0041]FIG. 20 is an ABS illustration of a top simple spin valve sensoremploying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Magnetic Disk Drive

[0042] Referring now to the drawings wherein like reference numeralsdesignate like or similar parts throughout the several views, FIGS. 1-3illustrate a magnetic disk drive 30. The drive 30 includes a spindle 32that supports and rotates a magnetic disk 34. The spindle 32 is rotatedby a motor 36 that is controlled by a motor controller 38. A combinedread and write magnetic head 40 is mounted on a slider 42 that issupported by a suspension 44 and actuator arm 46. A plurality of disks,sliders and suspensions may be employed in a large capacity directaccess storage device (DASD) as shown in FIG. 3. The suspension 44 andactuator arm 46 position the slider 42 so that the magnetic head 40 isin a transducing relationship with a surface of the magnetic disk 34.When the disk 34 is rotated by the motor 36 the slider is supported on athin (typically, 0.05 μm) cushion of air (air bearing) between thesurface of the disk 34 and the air bearing surface (ABS) 48. Themagnetic head 40 may then be employed for writing information tomultiple circular tracks on the surface of the disk 34, as well as forreading information therefrom. Processing circuitry 50 exchangessignals, representing such information, with the head 40, provides motordrive signals for rotating the magnetic disk 34, and provides controlsignals for moving the slider to various tracks. In FIG. 4 the slider 42is shown mounted to a suspension 44. The components describedhereinabove may be mounted on a frame 54 of a housing 55, as shown inFIG. 3.

[0043]FIG. 5 is an ABS view of the slider 42 and the magnetic head 40.The slider has a center rail 56 that supports the magnetic head 40, andside rails 58 and 60. The rails 56, 58 and 60 extend from a cross rail62. With respect to rotation of the magnetic disk 34, the cross rail 62is at a leading edge 64 of the slider and the magnetic head 40 is at atrailing edge 66 of the slider.

[0044]FIG. 6 is a side cross-sectional elevation view of the merged MRhead 40, which includes a write head portion 70 and a read head portion72, the read head portion employing an AP pinned spin valve sensor 74 ofthe present invention. FIG. 7 is an ABS view of FIG. 6. The spin valvesensor 74 is sandwiched between first and second gap layers 76 and 78,and the gap layers are sandwiched between first and second shield layers80 and 82. In response to external magnetic fields, the resistance ofthe spin valve sensor 74 changes. A sense current I_(S) conductedthrough the sensor causes these resistance changes to be manifested aspotential changes. These potential changes are then processed asreadback signals by the processing circuitry 50 shown in FIG. 3.

[0045] The write head portion of the merged MR head includes a coillayer 84 sandwiched between first and second insulation layers 86 and88. A third insulation layer 90 may be employed for planarizing the headto eliminate ripples in the second insulation layer caused by the coillayer 84. The first, second and third insulation layers are referred toin the art as an “insulation stack”. The coil layer 84 and the first,second and third insulation layers 86, 88 and 90 are sandwiched betweenfirst and second pole piece layers 92 and 94. The first and second polepiece layers 92 and 94 are magnetically coupled at a back gap 96 andhave first and second pole tips 98 and 100 which are separated by awrite gap layer 102 at the ABS. As shown in FIGS. 2 and 4, first andsecond solder connections 104 and 106 connect leads from the spin valvesensor 74 to leads 112 and 114 on the suspension 44, and third andfourth solder connections 116 and 118 connect leads 120 and 122 from thecoil 84 (see FIG. 8) to leads 124 and 126 on the suspension. In a mergedhead the second shield 82 for the read head 72 also serves as a firstpole piece 92 for the write head 70. In a piggyback head these areseparate layers.

[0046]FIG. 9 is an isometric ABS illustration of the read head 72 shownin FIG. 6. The read head 72 has a spin valve sensor 130 which will bedescribed in more detail hereinafter. First and second hard bias andlead layers 134 and 136 are connected to first and second side edges 138and 140 of the spin valve sensor. This connection is known in the art asa contiguous junction and is fully described in commonly assigned U.S.Pat. No. 5,018,037 which is incorporated by reference herein. The firsthard bias and lead layers include a first hard bias layer 140 and afirst lead layer 142 and the second hard bias and lead layers 136include a second hard bias layer 144 and a second lead layer 146. Thehard bias layers 140 and 144 cause magnetic flux to extendlongitudinally through the spin valve sensor 130 for stabilizingmagnetic domains of the free layer. The spin valve sensor 130 and thefirst and second hard bias and lead layers 134 and 136 are locatedbetween nonmagnetic electrically insulative first and second read gaplayers 148 and 150. The first and second gap layers 148 and 150 are, inturn, located between first and second shield layers 152 and 154.

First Investigation of a Simple Spin Valve Sensor

[0047]FIG. 10 shows a simple spin valve sensor 160 which includes aspacer layer (S) 162 of copper (Cu) between a pinned layer (P) 164 ofcobalt (Co) and a free layer (F) 166 of nickel iron (NiFe). An interfacelayer 168 of nickel iron (NiFe) may be located between the pinned layer164 and an antiferromagnetic (AFM) layer 170 of nickel oxide (NiO). TheAFM layer 170 pins the magnetic moment of the pinned layer 164 in adirection perpendicular to the ABS. The interface layer 168 is employedfor the purpose of promoting an exchange coupling between theantiferromagnetic layer 170 and the pinned layer 164. The free layer 166has a magnetic moment that is directed substantially parallel to the ABSand rotates in response to applied fields from a rotating magnetic diskat various angles relative to the pinned direction of the magneticmoment of the pinned layer 164. A capping layer of tantalum (Ta) 172 isshown on the free layer 166. The thicknesses of the layers are exemplaryand may be other thicknesses as desired. I have found that the cobaltpinned layer 164 has a low resistance, in the order of 10 to 12 Ω cm,and a high coercivity (H_(C)) in the order of 50 to 200 Oe. It would bedesirable if the resistivity of the pinned layer could be increased toreduce sense current shunting and if the coercivity of the pinned layercould be decreased so as to stabilize the direction of the moment of thepinned layer 164.

Present Simple Spin Valve Sensor

[0048] The present simple spin valve sensor 180 includes a spacer layer(S) 182 of copper (Cu) which is located between a pinned layer (P) 184of cobalt iron niobium hafnium (CoFeNbHf) and a free layer (F) 186 ofnickel iron. A giant magnetoresistive (GMR) enhancement layer 188 islocated between the pinned layer 184 and the spacer layer 182 for thepurpose of increasing the spin valve effect. It has been found that theGMR enhancement layer 188 interfaces the spacer layer 182 withoutintermixing therewith. An interface layer 190 is located between anantiferromagnetic layer (AFM) 192 and the pinned layer 184. Theinterface layer 190 serves the same function as the interface layer 168in FIG. 10. The AFM layer 192 pins the magnetic moment of the interfacelayer 190 perpendicular to the ABS which, in turn, pins the magneticmoment of the pinned layer 184 perpendicular to the ABS. A capping layer194 is located on the free layer 186 for protecting the free layer 186from subsequent layers and subsequent processing steps. The cobalt ironniobium hafnium (CoFeNbHf) material employed for the pinned layer 184has a resistivity of 110 ohms and a coercivity (H_(C)) of 5 to 10 Oe.This resistivity is significantly higher than the resistivity of thecobalt layer 164 in FIG. 10 and shunts considerably less of the sensecurrent. Further, the significantly lower coercivity of 5 to 10 Oe, ascompared to 50 to 200 Oe for the pinned layer 164 in FIG. 10, results ina more stable pinning of the magnetic moment of the pinned layer 184.

Second Investigation of AP Pinned Spin Valve Sensor

[0049]FIG. 12 shows an AP pinned spin valve sensor 200 investigated byme. The sensor 200 includes a spacer layer (S) 202 of copper (Cu)between an AP pinned layer 204 and a free layer (F) 206 of nickel iron(NiFe). The AP pinned layer 204 includes a ruthenium (Ru) layer 208which is located between a first ferromagnetic layer 210 of cobalt and asecond ferromagnetic layer 212 of cobalt. The thicknesses of each of thecobalt layers 210 and 212 may be 24 Å and the thickness of the rutheniumlayer 208 may be 8 Å. An interface layer 214 of nickel iron (NiFe) islocated between an antiferromagnetic layer (AFM) 216 of nickel oxide(NiO) and the first cobalt layer 210 of the AP pinned layer. A cappinglayer 218 is located on the free layer 206. The thicknesses of thelayers shown in FIG. 12 are exemplary and may be changed as desired. Ifound that the first and second cobalt layers 210 and 212 exhibit lowresistivity, in the order of 10 to 12 ohms, and high coercivity (H_(C)),in the order of 50 to 200 Oe. Accordingly, the cobalt layers 210 and 212shunt a significant amount of the sense current due to their lowresistivity and can be magnetically unstable due to a coercivity (H_(C))in the range of 50 to 200 Oe.

Various Embodiments of the Present AP Pinned Spin Valve Sensor

[0050] A first embodiment of the present AP pinned spin valve sensor 300is shown in FIG. 13. The spin valve sensor 300 includes a spacer layer(S) 302 of copper (Cu) which is located between an AP pinned layer 304and a free layer (F) 306 of nickel iron (NiFe). The AP pinned layer 304includes a ruthenium (Ru) layer 308 which is located between a firstferromagnetic layer 310 of cobalt iron niobium hafnium (CoFeNbHf) and asecond ferromagnetic layer 312 of cobalt (Co). The ruthenium (Ru) layer308 maybe 8 Å thick, the cobalt iron niobium hafnium (CoFeNbHf) layer310 may 35 Å thick and the cobalt (Co) layer 312 may be 24 Å thick. Thecobalt iron niobium hafnium (CoFeNbHf) material of the layer 310 has aresistivity which is significantly higher than the resistivity of thecobalt layer 210 in FIG. 12 and has a coercivity (H_(C)) which issignificantly lower than the coercivity of the cobalt layer 210 in FIG.12. Accordingly, the layer 310 shunts very little of the sense currentand is magnetically more stable than the cobalt layer 210 in FIG. 12.The cobalt layer 312 serves a double function, namely serving as apinned layer for scattering of conduction electrons upon rotation of thefree layer 306 and serving as a GMR enhancement layer because of itsinterfacing with the spacer layer 302, as discussed in regard to theembodiment 180 in FIG. 11. Accordingly, in the embodiment 300 in FIG. 13the cobalt iron niobium hafnium (CoFeNbHf) is employed for only one ofthe ferromagnetic pinned layers of the AP pinned layer 304. The APpinned spin valve sensor 300 in FIG. 13 further includes an interfacelayer 314 which is located between an antiferromagnetic (AFM) layer 316of nickel oxide (NiO). A capping layer 318 of tantalum (Ta) may beemployed on top of the free layer 306. Again, the thicknesses shown forthe various layers are exemplary and may be changed as desired.

[0051] A second embodiment of the present AP pinned spin valve sensor400 is shown in FIG. 14. In this embodiment a spacer layer (S) 402 ofcopper (Cu) is located between an AP pinned layer 404 and a free layer(F) 406 of nickel iron (NiFe). The AP pinned layer 404 includes aruthenium (Ru) layer 408 which is located between first and secondferromagnetic layers 410 and 412. The first ferromagnetic layer 410includes a first film 414 of cobalt iron niobium hafnium (CoFeNbHf) anda second film 416 of cobalt (Co). The first film 414 may be 25 Å thickand the second film 416 may be 5 Å thick. The second ferromagnetic layer412 is cobalt (Co) and may be 24 Å thick. The cobalt layer 416 of thefirst ferromagnetic layer 410 provides an improved interfacing betweenthe cobalt iron niobium hafnium (CoFeNbHf) layer 414 and the ruthenium(Ru) layer 408. The cobalt iron niobium hafnium (CoFeNbHf) layer 414reduces sense current shunting in the first ferromagnetic layer 410 andincreases the magnetic stability thereof. In the same manner as thecobalt layer 312 in FIG. 13, the cobalt layer 412 in FIG. 14 serves adouble function as a pinned layer and as an improved interface with thespacer layer (S) 402 for increasing the GMR effect. An interface layer418 of nickel iron (NiFe) is located between the antiferromagnetic (AFM)layer 420 and the cobalt iron niobium hafnium (CoFeNbHf) film 414. Acapping layer of tantalum (Ta) is located on the free layer (F) 406. Thethicknesses shown for the various layers in FIG. 14 are exemplary andmay be changed as desired.

[0052] A third embodiment of the present AP pinned spin valve sensor 500is illustrated in FIG. 15. This embodiment includes a spacer layer (S)502 of copper (Cu) which is located between an AP pinned layer 504 and afree layer (F) 506 of nickel iron (NiFe). The AP pinned layer 504includes a ruthenium (Ru) layer 508 which is located between a cobaltiron niobium hafnium (CoFeNbHf) layer 510 and a second cobalt ironniobium hafnium (CoFeNbHf) layer 512. The ruthenium layer 508 is 8 Åthick, the first layer 510 is 35 Å thick and the second layer 512 is 35Å thick. The high resistivity of the first and second layers 510 and 512is the best embodiment of the AP pinned layer 504 for reducing sensecurrent shunting. Further, it is desirable to use the cobalt ironniobium hafnium (CoFeNbHf) material for both of the first and secondferromagnetic layers 510 and 512 of the AP pinned layer 504 foroptimizing the stability of the magnetic moments of the layers 510 and512. By employing the cobalt iron niobium hafnium (CoFeNbHf) materialfor the second ferromagnetic layer 512, a return of its magnetic momentto its original position is enabled in the same manner that the magneticmoment of the first ferromagnetic layer 510 is returned to its originalposition. Accordingly, in a preferred embodiment, cobalt iron niobiumhafnium (CoFeNbHf) is utilized in the layers on each side of theruthenium (Ru) layer 508. An interface layer 512 of nickel iron (NiFe)is employed between the antiferromagnetic (AFM) layer 514 and the cobaltiron niobium hafnium (CoFeNbHf) layer 510. A capping layer 516 islocated on the free layer (F) 506.

[0053] A fourth embodiment of the present AP pinned spin valve sensor600 is illustrated in FIG. 16. This embodiment includes a spacer layer(S) 602 of copper (Cu) located between an AP pinned layer 604 and a freelayer (F) 606 of nickel iron (NiFe). The AP pinned layer 604 includes aruthenium layer (Ru) 608 which is located between a first ferromagneticlayer of cobalt iron niobium hafnium (CoFeNbHf) 610 and a secondferromagnetic layer of cobalt iron niobium hafnium (CoFeNbHf) 612. Thethickness of the ruthenium (Ru) layer may be 8 Å thick, the thickness ofthe first ferromagnetic layer 610 may be 35 Å thick and the thickness ofthe second ferromagnetic layer 612 may be 20 Å thick. This embodimenthas a similar advantage to the embodiment 500 shown in FIG. 15 in thatthe cobalt iron niobium hafnium (CoFeNbHf) material is used for both thefirst and second ferromagnetic layers 610 and 612 for reducing sensecurrent shunting and increasing the magnetic stability of both of thefirst and second ferromagnetic layers 610 and 612. In addition, however,a cobalt layer (Co) 614 is employed between the AP pinned layer 604 andthe spacer (S) layer 602. The cobalt layer 614 serves as a GMRenhancement layer in the same manner as the layer 312 in FIG. 13 and thelayer 412 in FIG. 14. An interface layer 616 of nickel iron (NiFe) islocated between an antiferromagnetic (AFM) layer 618 and the firstferromagnetic layer 610 of the AP pinned layer. A capping layer 620 islocated on the free layer (F) 606.

[0054] A fifth embodiment of the present AP pinned spin valve sensor 700is shown in FIG. 17. This embodiment includes a spacer layer (S) 702which is located between an AP pinned layer 704 and a free layer (F) 706of nickel iron (NiFe). The AP pinned layer 704 includes a ruthenium (Ru)layer 708 between a first ferromagnetic layer 710 and a secondferromagnetic layer 712. The first ferromagnetic layer 710 includes afirst film 714 of cobalt iron niobium hafnium (CoFeNbHf) and a secondfilm 716 of cobalt (Co). The first film 714 may be 25 Å thick and thesecond film 716 may be 5 Å thick. The second ferromagnetic layer 712 ismade from cobalt iron niobium hafnium (CoFeNbHf) and may be 20 Å thick.The AP pinned layer 704 in FIG. 17 has the same advantages as the APpinned layer 604 in FIG. 16 regarding resistivity and coercivity.Further, the AP pinned layer 704 in FIG. 17 employs the second film 710of cobalt (Co) between the first film 714 and the ruthenium (Ru) layer708 because of its improved interfacing with each of the layers 714 and708. A GMR enhancement layer 718 of cobalt (Co), which may be 10 Åthick, is located between the AP pinned layer 704 and the spacer layer(S) 702. This cobalt layer 718 provides improved interfacing with thelayers 712 and 702 and increases the GMR effect. An interface layer 720of nickel iron (NiFe) is employed between the antiferromagnetic (AFM)layer 722 of nickel oxide (NiO) and the first film 714 of the AP pinnedlayer 704.

[0055] A sixth embodiment of the present AP pinned spin valve sensor 800is shown in FIG. 18. This embodiment includes a spacer layer (S) ofcopper (Cu) 802 located between an AP pinned layer 804 and a free layer(F) layer 806 of nickel iron (NiFe). The pinned layer 804 includes aruthenium (Ru) layer 808 located between first and second ferromagneticlayers 810 and 812. The first ferromagnetic layer 810 may include afirst film 814 of cobalt iron niobium hafnium (CoFeNbHf) and a secondfilm of cobalt (Co). The film 814 may be 25 Å thick and the second film816 may be 5 Å thick. The second ferromagnetic layer 812 includes afirst film 818 of cobalt (Co) and a second film 820 of cobalt ironniobium hafnium (CoFeNbHf). The first film 818 may be 5 Å thick and thesecond film 820 may be 15 Å thick. The AP pinned layer 804 in FIG. 18has the advantage of high resistivity to prevent current shunting andlow coercivity to promote magnetic stability because of the cobalt ironniobium hafnium (CoFeNbHf) material employed for the films 814 and 820.The AP pinned layer 804 has a further advantage by employing films 816and 818 of cobalt (Co) on each side of the ruthenium (Ru) layer 808 forpromoting a better interface between the layers. A GMR enhancement layer822 of cobalt (Co) may be employed between the AP pinned layer 804 andthe spacer layer (S) 802 for enhancing the GMR effect. The thickness ofthis layer may be 10 Å. An interface layer 824 of nickel iron (NiFe) isemployed between the antiferromagnetic (AFM) layer 826 and the firstfilm 814 of the AP pinned layer. A capping layer 828 of tantalum (Ta)may be employed on the free layer (F) 806. The thicknesses of the layersshown in FIG. 18 are exemplary and may be changed as desired.

[0056] A seventh embodiment of the present AP pinned spin valve sensor900 is shown in FIG. 19. This sensor 900 differs from the sensors shownin FIGS. 13-18 in that the sensor in FIG. 19 is a top spin valve sensorwhereas the spin valve sensors in FIGS. 13-18 are bottom spin valvesensors. A top spin valve sensor has the pinning layer located at thetop whereas a bottom spin valve sensor has the pinning layer located atthe bottom. The embodiment in FIG. 19 includes a spacer layer (S) 902 ofcopper (Cu) which is located between an AP pinned layer 904 and a freelayer (F) 906 of nickel iron (NiFe). The AP pinned layer 904 includes aruthenium (Ru) layer 908 located between a cobalt iron niobium hafnium(CoFeNbHf) layer 910 and a cobalt iron niobium hafnium (CoFeNbHf) layer912. The AP pinned layer 904 in FIG. 19 will have the same advantages asthe pinned layer 504 in FIG. 15 by providing high resistivity to lessencurrent shunting and low coercivity to promote magnetic stability of theAP pinned layer. An antiferromagnetic layer (AFM) 914 of nickelmanganese (NiMn) is exchange coupled to the cobalt iron niobium hafnium(CoFeNbHf) layer 912 for pinning its magnetic moment perpendicular tothe ABS.

[0057] A tantalum layer 930 is located adjacent the antiferromagnetic(AFM) layer 914. The embodiment 900 is shown for the purpose ofillustrating that any one of the embodiments in FIGS. 13-18 may be a topspin valve sensor instead of a bottom spin valve sensor and still employthe concepts of the present invention. The thicknesses shown for thevarious layers in FIG. 19 are exemplary and may be changed as desired.

[0058] An interface layer of cobalt (Co) 918 may be located between theAFM layer 914 and the film 912 of the AP pinned layer for providing abetter exchange coupling between the layers 914 and 912. Accordingly,the AFM layer 914 is exchange coupled to the interface layer 918 whichis, in turn, exchange coupled to the layer 912. Further, interfacelayers 920 and 922 of the AP pinned layer 904 may interface theruthenium (Ru) layer 908 and the first and second cobalt iron niobiumhafnium (CoFeNbHf) layers 910 and 912 for promoting exchange couplingbetween these layers. GMR enhancement layers 924 and 926 may be employedfor interfacing the spacer layer 902 and a respective one of the freelayer 906 and the first ferromagnetic layer 910 of cobalt iron niobiumhafnium (CoFeNbHf) 910 of the AP pinned layer.

[0059] An exemplary top simple spin valve 1000 is illustrated in FIG. 20wherein the antiferromagnetic layer (AFM) 1002 of nickel manganese(NiMn) is located at the top of the spin valve structure. A spacer layer1004 of copper (Cu) is located between a pinned layer (P) 1006 of cobaltiron niobium hafnium (CoFeNbHf) and a free layer (F) 1008 of nickel iron(NiFe). A GMR enhancement layer 1010 of cobalt (Co) may be employedbetween the free layer 1008 and the spacer layer 1004 for enhancing theGMR effect. An interface layer 1012 of cobalt (Co) may be employedbetween the AFM layer 1002 and the pinned layer 1006 for improving theexchange coupling between these layers and an interface layer 1014 ofcobalt (Co) may be employed between the pinned layer 1006 and the spacerlayer 1004. The thicknesses for the various layers shown in FIG. 20 areexemplary and may be changed as desired.

Alternatives of the Present Invention

[0060] Other materials that may be substituted for the cobalt ironniobium hafnium (CoFeNbHf) material for the various layers described inFIGS. 11 and 13-19 are cobalt niobium hafnium (CoNbHf), cobalt ironniobium (CoFeNb) and cobalt iron hafnium (CoFeHf). Other materialssuitable for the cobalt (Co) layers described in FIGS. 11 and 13-19 arecobalt iron (CoFe) and cobalt iron boron (CoFeB). The preferred atomicweight percentages for the cobalt iron niobium hafnium (CoFeNbHf)material are 86.5/0.5/11/2. The nickel iron layers are preferablyNi₈₀Fe₂₀.

[0061] Clearly, other embodiments and modifications of this inventionwill occur readily to those of ordinary skill in the art in view ofthese teachings. For instance, the spin valve sensor may be employed forpurposes other than in a magnetic disk drive, such as a tape drivesearch and/or surveillance devices and laboratory equipment. Therefore,this invention is to be limited only by the following claims, whichinclude all such embodiments and modifications when viewed inconjunction with the above specification and the accompanying drawings.

I claim:
 1. A spin valve sensor comprising: an antiferromagnetic pinninglayer having magnetic spins oriented in a first direction; aferromagnetic pinned layer exchange coupled to the pinning layer andhaving a magnetic moment pinned by the pinned layer in said firstdirection; said pinned layer being selected from a group comprisingcobalt iron niobium hafnium (CoFeNbHf), cobalt iron niobium (CoFeNb),cobalt iron hafnium (CoFeHf) and cobalt niobium hafnium (CoNbHf); anonmagnetic electrically conductive spacer layer; a ferromagnetic freelayer that has a magnetic moment that is free to rotate in response toapplied fields; and the spacer layer being located between the pinnedlayer and the free layer.
 2. A spin valve sensor as claimed in claim 1including: the pinning layer being nickel oxide (NiO); and an interfacelayer of nickel iron (NiFe) having first and second surfaces, the firstsurface being exchange coupled to the pinning layer and the secondsurface being exchange coupled to the pinned layer.
 3. A spin valvesensor as claimed in claim 2 wherein the pinned layer is cobalt ironniobium hafnium (CoFeNbHf).
 4. A spin valve sensor as claimed in claim 3including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 5. A spin valve sensoras claimed in claim 1 wherein: the antiferromagnetic layer is selectedfrom the group comprising nickel manganese (NiMn), platinum manganese(PtMn) and iridium manganese (IrMn).
 6. A spin valve sensor as claimedin claim 5 wherein the pinned layer is cobalt iron niobium hafnium(CoFeNbHf).
 7. A spin valve sensor as claimed in claim 6 including: agiant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 8. A spin valve sensor as claimed in claim1 wherein the pinned layer is an antiparallel (AP) pinned layer thatincludes: first and second ferromagnetic layers wherein the firstferromagnetic layer is exchange coupled to the pinning layer and has amagnetic moment pinned in said first direction; a ruthenium spacer layerlocated between the first and second ferromagnetic layers so that thesecond ferromagnetic layer has a magnetic moment that is pinned in asecond direction that is antiparallel to said first direction; and atleast one of the first and second ferromagnetic layers being selectedfrom the group comprising cobalt iron niobium hafnium (CoFeNbHf), cobaltiron niobium (CoFeNb), cobalt iron hafnium (CoFeHf) and cobalt niobiumhafnium (CoNbHf).
 9. A spin valve sensor as claimed in claim 8including: the pinning layer being nickel oxide (NiO); and an interfacelayer of nickel iron (NiFe) having first and second surfaces, the firstsurface being exchange coupled to the pinning layer and the secondsurface being exchange coupled to the pinned layer.
 10. A spin valvesensor as claimed in claim 9 wherein said at least one of said first andsecond ferromagnetic layers is cobalt iron niobium hafnium (CoFeNbHf).11. A spin valve sensor as claimed in claim 10 wherein the secondferromagnetic layer is cobalt (Co).
 12. A spin valve sensor as claimedin claim 11 including: a giant magnetoresistive (GMR) enhancement layerof cobalt (Co); the GMR enhancement layer being located between thepinned and spacer layers and interfacing the spacer layer.
 13. A spinvalve sensor as claimed in claim 9 wherein: the first ferromagneticlayer includes first and second films, the first film being selectedfrom said group and the second film being cobalt (Co) and being locatedbetween the first film and the ruthenium (Ru) spacer layer; and thesecond ferromagnetic layer being cobalt (Co).
 14. A spin valve sensor asclaimed in claim 13 wherein the first film is cobalt iron niobiumhafnium (CoFeNbHf).
 15. A spin valve sensor as claimed in claim 14including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 16. A spin valve sensoras claimed in claim 9 wherein each of the first and second ferromagneticlayers is selected from the group.
 17. A spin valve sensor as claimed inclaim 16 wherein each of the first and second films is cobalt ironniobium hafnium (CoFeNbHf).
 18. A spin valve sensor as claimed in claim17 including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 19. A spin valve sensoras claimed in claim 9 wherein: the first ferromagnetic layer has firstand second films and the second ferromagnetic layer has a first film;each of the first films being selected from the group and the secondfilm of the first ferromagnetic layer being cobalt (Co); and theruthenium (Ru) spacer layer having first and second surfaces with thefirst surface interfacing the second film of the first ferromagneticlayer and the second surface interfacing the first film of the secondferromagnetic layer.
 20. A spin valve sensor as claimed in claim 19wherein each of the first films is cobalt iron niobium hafnium(CoFeNbHf).
 21. A spin valve sensor as claimed in claim 20 including: agiant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 22. A spin valve sensor as claimed inclaim 9 wherein: each of the first and second ferromagnetic layersincludes first and second films; the first film of the firstferromagnetic layer and the second film of the second ferromagneticlayer being selected from the group; the second film of the firstferromagnetic layer and the first film of the second ferromagnetic layerbeing cobalt (Co); and the ruthenium (Ru) spacer layer having first andsecond surfaces with the first surface interfacing the second film ofthe first ferromagnetic layer and the second surface interfacing thefirst film of the second ferromagnetic layer.
 23. A spin valve sensor asclaimed in claim 22 wherein each of the first film of the firstferromagnetic layer and the second film of the second ferromagneticlayer is cobalt iron niobium hafnium (CoFeNbHf).
 24. A spin valve sensoras claimed in claim 23 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 25. A spin valve sensor as claimed in claim 8 wherein: theantiferromagnetic layer is selected from the group comprising nickelmanganese (NiMn), platinum manganese (PtMn) and iridium manganese(IrMn).
 26. A spin valve sensor as claimed in claim 25 wherein said atleast one of said first and second ferromagnetic layers is cobalt ironniobium hafnium (CoFeNbHf).
 27. A spin valve sensor as claimed in claim26 wherein the second ferromagnetic layer is cobalt (Co).
 28. A spinvalve sensor as claimed in claim 27 including: a giant magnetoresistive(GMR) enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 29. A spin valve sensor as claimed in claim 25 wherein: the firstferromagnetic layer includes first and second films, the first filmbeing selected from said group and the second film being cobalt (Co) andbeing located between the first film and the ruthenium (Ru) spacerlayer; and the second ferromagnetic layer being cobalt (Co).
 30. A spinvalve sensor as claimed in claim 29 wherein the first film is cobaltiron niobium hafnium (CoFeNbHf).
 31. A spin valve sensor as claimed inclaim 30 including: a giant magnetoresistive (GMR) enhancement layer ofcobalt (Co); the GMR enhancement layer being located between the pinnedand spacer layers and interfacing the spacer layer.
 32. A spin valvesensor as claimed in claim 25 wherein each of the first and secondferromagnetic layers is selected from the group.
 33. A spin valve sensoras claimed in claim 32 wherein each of the first and second films iscobalt iron niobium hafnium (CoFeNbHf).
 34. A spin valve sensor asclaimed in claim 33 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 35. A spin valve sensor as claimed in claim 25 wherein: the firstferromagnetic layer has first and second films and the secondferromagnetic layer has a first film; each of the first films beingselected from the group and the second film of the first ferromagneticlayer being cobalt (Co); and the ruthenium (Ru) spacer layer havingfirst and second surfaces with the first surface interfacing the secondfilm of the first ferromagnetic layer and the second surface interfacingthe first film of the second ferromagnetic layer.
 36. A spin valvesensor as claimed in claim 35 wherein each of the first films is cobaltiron niobium hafnium (CoFeNbHf).
 37. A spin valve sensor as claimed inclaim 36 including: a giant magnetoresistive (GMR) enhancement layer ofcobalt (Co); the GMR enhancement layer being located between the pinnedand spacer layers and interfacing the spacer layer.
 38. A spin valvesensor as claimed in claim 25 wherein: each of the first and secondferromagnetic layers includes first and second films; the first film ofthe first ferromagnetic layer and the second film of the secondferromagnetic layer being selected from the group; the second film ofthe first ferromagnetic layer and the first film of the secondferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 39. A spin valve sensor as claimed in claim 38 wherein each ofthe first film of the first ferromagnetic layer and the second film ofthe second ferromagnetic layer is cobalt iron niobium hafnium(CoFeNbHf).
 40. A spin valve sensor as claimed in claim 39 including: agiant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 41. A spin valve sensor as claimed inclaim 1 wherein the pinned layer is a single layer.
 42. A spin valvesensor as claimed in claim 41 including: the pinning layer being nickeloxide (NiO); and an interface layer of nickel iron (NiFe) having firstand second surfaces, the first surface being exchange coupled to thepinning layer and the second surface being exchange coupled to thepinned layer.
 43. A spin valve sensor as claimed in claim 42 including:a giant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 44. A spin valve sensor as claimed inclaim 43 including: a giant magnetoresistive (GMR) enhancement layer ofcobalt (Co); the GMR enhancement layer interfacing the spacer layer in alocation between the pinned layer and the spacer layer.
 45. A spin valvesensor as claimed in claim 41 wherein: the antiferromagnetic layer isselected from the group comprising nickel manganese (NiMn), platinummanganese (PtMn) and iridium manganese (IrMn).
 46. A spin valve sensoras claimed in claim 45 wherein the pinned layer is cobalt iron niobiumhafnium (CoFeNbHf).
 47. A spin valve sensor as claimed in claim 46including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 48. A magnetic head thathas an air bearing surface (ABS) comprising: a read head that includes:first and second ferromagnetic shield layers: first and secondnonmagnetic electrically insulative gap layers located between the firstand second ferromagnetic shield layers; a spin valve sensor responsiveto applied magnetic fields; the spin valve sensor being located betweenthe first and second gap layers; and first and second electricallyconductive lead layers located between the first and second gap layersand connected to the spin valve sensor for conducting a sense currentthrough the spin valve sensor; the spin valve sensor including: anantiparallel (AP) pinned layer including first and second ferromagneticlayers and a ruthenium (Ru) layer wherein the ruthenium (Ru) layer issandwiched between the first and second ferromagnetic layers; a pinninglayer that has magnetic spins oriented in a first predetermineddirection that is perpendicular to the ABS; the AP pinned layer beingexchange coupled to the pinning layer with the first ferromagnetic layerinterfacing the pinning layer so that a magnetic moment of the secondferromagnetic layer is pinned in a second predetermined direction thatis antiparallel to said first predetermined direction; at least one ofthe first and second ferromagnetic layers being selected from the groupcomprising cobalt iron niobium hafnium (CoFeNbHf), cobalt iron niobium(CoFeNb), cobalt iron hafnium (CoFeHf) and cobalt niobium hafnium(CoNbHf); a free layer that has a magnetic moment that is free to rotaterelative to the second predetermined direction of the AP pinned layer inresponse to an applied field; a nonmagnetic electrically conductivefirst spacer layer; and the first spacer layer being located between thefree layer and the AP pinned layer.
 49. A magnetic head as claimed inclaim 48 wherein the pinned layer is cobalt iron niobium hafnium(CoFeNbHf).
 50. A magnetic head as claimed in claim 49 including: agiant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 51. A magnetic head as claimed in claim 50including: a write head including: first and second pole piece layersand a write gap layer; the first and second pole piece layers beingseparated by the write gap layer at the ABS and connected at a back gapthat is recessed rearwardly in the head from the ABS; an insulationstack having at least first and second insulation layers; at least onecoil layer embedded in the insulation stack; and the insulation stackand the at least one coil layer being located between the first andsecond pole piece layers.
 52. A magnetic head as claimed in claim 51including: the pinning layer being nickel oxide (NiO); and an interfacelayer of nickel iron (NiFe) having first and second surfaces, the firstsurface being exchange coupled to the pinning layer and the secondsurface being exchange coupled to the pinned layer.
 53. A magnetic headas claimed in claim 52 wherein said at least one of said first andsecond ferromagnetic layers is cobalt iron niobium hafnium (CoFeNbHf).54. A magnetic head as claimed in claim 53 wherein the secondferromagnetic layer is cobalt (Co).
 55. A magnetic head as claimed inclaim 54 including: a giant magnetoresistive (GMR) enhancement layer ofcobalt (Co); the GMR enhancement layer being located between the pinnedand spacer layers and interfacing the spacer layer.
 56. A magnetic headas claimed in claim 52 wherein: the first ferromagnetic layer includesfirst and second films, the first film being selected from said groupand the second film being cobalt (Co) and being located between thefirst film and the ruthenium (Ru) spacer layer; and the secondferromagnetic layer being cobalt (Co).
 57. A magnetic head as claimed inclaim 56 wherein the first film is cobalt iron niobium hafnium(CoFeNbHf).
 58. A magnetic head as claimed in claim 57 including: agiant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 59. A magnetic head as claimed in claim 52wherein each of the first and second ferromagnetic layers is selectedfrom the group.
 60. A magnetic head as claimed in claim 59 wherein eachof the first and second films is cobalt iron niobium hafnium (CoFeNbHf).61. A magnetic head as claimed in claim 60 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 62. A magnetic head as claimed in claim 52wherein: the first ferromagnetic layer has first and second films andthe second ferromagnetic layer has a first film; each of the first filmsbeing selected from the group and the second film of the firstferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 63. A magnetic head as claimed in claim 62 wherein each of thefirst films is cobalt iron niobium hafnium (CoFeNbHf).
 64. A magnetichead as claimed in claim 63 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 65. A magnetic head as claimed in claim 52 wherein: each of thefirst and second ferromagnetic layers includes first and second films;the first film of the first ferromagnetic layer and the second film ofthe second ferromagnetic layer being selected from the group; the secondfilm of the first ferromagnetic layer and the first film of the secondferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 66. A magnetic head as claimed in claim 65 wherein each of thefirst film of the first ferromagnetic layer and the second film of thesecond ferromagnetic layer is cobalt iron niobium hafnium (CoFeNbHf).67. A magnetic head as claimed in claim 66 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer interfacing the spacer layer in a location between thepinned layer and the spacer layer.
 68. A magnetic head as claimed inclaim 51 wherein: the antiferromagnetic layer is selected from the groupcomprising nickel manganese (NiMn), platinum manganese (PtMn) andiridium manganese (IrMn).
 69. A magnetic head as claimed in claim 68wherein said at least one of said first and second ferromagnetic layersis cobalt iron niobium hafnium (CoFeNbHf).
 70. A magnetic head asclaimed in claim 69 wherein the second ferromagnetic layer is cobalt(Co).
 71. A magnetic head as claimed in claim 70 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 72. A magnetic head as claimed in claim 68wherein: the first ferromagnetic layer includes first and second films,the first film being selected from said group and the second film beingcobalt (Co) and being located between the first film and the ruthenium(Ru) spacer layer; and the second ferromagnetic layer being cobalt (Co).73. A magnetic head as claimed in claim 72 wherein the first film iscobalt iron niobium hafnium (CoFeNbHf).
 74. A magnetic head as claimedin claim 73 including: a giant magnetoresistive (GMR) enhancement layerof cobalt (Co); the GMR enhancement layer being located between thepinned and spacer layers and interfacing the spacer layer.
 75. Amagnetic head as claimed in claim 68 wherein each of the first andsecond ferromagnetic layers is selected from the group.
 76. A magnetichead as claimed in claim 75 wherein each of the first and second filmsis cobalt iron niobium hafnium (CoFeNbHf).
 77. A magnetic head asclaimed in claim 76 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 78. A magnetic head as claimed in claim 68 wherein: the firstferromagnetic layer has first and second films and the secondferromagnetic layer has a first film; each of the first films beingselected from the group and the second film of the first ferromagneticlayer being cobalt (Co); and the ruthenium (Ru) spacer layer havingfirst and second surfaces with the first surface interfacing the secondfilm of the first ferromagnetic layer and the second surface interfacingthe first film of the second ferromagnetic layer.
 79. A magnetic head asclaimed in claim 78 wherein each of the first films is cobalt ironniobium hafnium (CoFeNbHf).
 80. A magnetic head as claimed in claim 79including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 81. A magnetic head asclaimed in claim 68 wherein: each of the first and second ferromagneticlayers includes first and second films; the first film of the firstferromagnetic layer and the second film of the second ferromagneticlayer being selected from the group; the second film of the firstferromagnetic layer and the first film of the second ferromagnetic layerbeing cobalt (Co); and the ruthenium (Ru) spacer layer having first andsecond surfaces with the first surface interfacing the second film ofthe first ferromagnetic layer and the second surface interfacing thefirst film of the second ferromagnetic layer.
 82. A magnetic head asclaimed in claim 81 wherein each of the first film of the firstferromagnetic layer and the second film of the second ferromagneticlayer is cobalt iron niobium hafnium (CoFeNbHf).
 83. A magnetic head asclaimed in claim 82 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 84. A magnetic disk drive that includes at least one magnetichead that has an air bearing surface (ABS), the disk drive comprising:the magnetic head including a combined read head and write head; theread head including: first and second ferromagnetic shield layers: firstand second nonmagnetic electrically insulative gap layers locatedbetween the first and second ferromagnetic shield layers; a spin valvesensor responsive to applied magnetic fields; the spin valve sensorbeing located between the first and second gap layers; and first andsecond electrically conductive lead layers located between the first andsecond gap layers and connected to the spin valve sensor for conductinga sense current through the spin valve sensor; the spin valve sensorincluding: an antiparallel (AP) pinned layer including first and secondferromagnetic layers and a ruthenium (Ru) layer wherein the ruthenium(Ru) layer is sandwiched between the first and second ferromagneticlayers; a pinning layer that has magnetic spins oriented in a firstpredetermined direction that is perpendicular to the ABS; the AP pinnedlayer being exchange coupled to the pinning layer with the firstferromagnetic layer interfacing the pinning layer so that a magneticmoment of the second ferromagnetic layer is pinned in a secondpredetermined direction that is antiparallel to said first predetermineddirection; at least one of the first and second ferromagnetic layersbeing selected from the group comprising cobalt iron niobium hafnium(CoFeNbHf), cobalt iron niobium (CoFeNb), cobalt iron hafnium (CoFeHf)and cobalt niobium hafnium (CoNbHf); a free layer that has a magneticmoment that is free to rotate relative to the second predetermineddirection of the AP pinned layer in response to an applied field; anonmagnetic electrically conductive first spacer layer; the first spacerlayer being located between the free layer and the AP pinned layer, thewrite head including: first and second pole piece layers and a write gaplayer; the first and second pole piece layers being separated by thewrite gap layer at the ABS and connected at a back gap that is recessedrearwardly in the head from the ABS; an insulation stack having at leastfirst and second insulation layers; at least one coil layer embedded inthe insulation stack; the insulation stack and the at least one coillayer being located between the first and second pole piece layers; andthe second shield layer and the first pole piece layer being a commonlayer; a housing; a magnetic disk rotatably supported in the housing; asupport mounted in the housing for supporting the magnetic head with itsABS facing the magnetic disk so that the magnetic head is in atransducing relationship with the magnetic disk; means for rotating themagnetic disk; positioning means connected to the support for moving themagnetic head to multiple positions with respect to said magnetic disk;and processing means connected to the magnetic head, to the means forrotating the magnetic disk and to the positioning means for exchangingsignals with the merged magnetic head, for controlling movement of themagnetic disk and for controlling the position of the magnetic head. 85.A magnetic disk drive as claimed in claim 84 including: the pinninglayer being nickel oxide (NiO); and an interface layer of nickel iron(NiFe) having first and second surfaces, the first surface beingexchange coupled to the pinning layer and the second surface beingexchange coupled to the pinned layer.
 86. A magnetic disk drive asclaimed in claim 85 wherein said at least one of said first and secondferromagnetic layers is cobalt iron niobium hafnium (CoFeNbHf).
 87. Amagnetic disk drive as claimed in claim 86 wherein the secondferromagnetic layer is cobalt (Co).
 88. A magnetic disk drive as claimedin claim 87 including: a giant magnetoresistive (GMR) enhancement layerof cobalt (Co); the GMR enhancement layer being located between thepinned and spacer layers and interfacing the spacer layer.
 89. Amagnetic disk drive as claimed in claim 85 wherein: the firstferromagnetic layer includes first and second films, the first filmbeing selected from said group and the second film being cobalt (Co) andbeing located between the first film and the ruthenium (Ru) spacerlayer; and the second ferromagnetic layer being cobalt (Co).
 90. Amagnetic disk drive as claimed in claim 89 wherein the first film iscobalt iron niobium hafnium (CoFeNbHf).
 91. A magnetic disk drive asclaimed in claim 90 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 92. A magnetic disk drive as claimed in claim 85 wherein each ofthe first and second ferromagnetic layers is selected from the group.93. A magnetic disk drive as claimed in claim 92 wherein each of thefirst and second films is cobalt iron niobium hafnium (CoFeNbHf).
 94. Amagnetic disk drive as claimed in claim 93 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 95. A magnetic disk drive as claimed inclaim 85 wherein: the first ferromagnetic layer has first and secondfilms and the second ferromagnetic layer has a first film; each of thefirst films being selected from the group and the second film of thefirst ferromagnetic layer being cobalt (Co); and the ruthenium (Ru)spacer layer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 96. A magnetic disk drive as claimed in claim 95 wherein each ofthe first films is cobalt iron niobium hafnium (CoFeNbHf).
 97. Amagnetic disk drive as claimed in claim 96 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 98. A magnetic disk drive as claimed inclaim 85 wherein: each of the first and second ferromagnetic layersincludes first and second films; the first film of the firstferromagnetic layer and the second film of the second ferromagneticlayer being selected from the group; the second film of the firstferromagnetic layer and the first film of the second ferromagnetic layerbeing cobalt (Co); and the ruthenium (Ru) spacer layer having first andsecond surfaces with the first surface interfacing the second film ofthe first ferromagnetic layer and the second surface interfacing thefirst film of the second ferromagnetic layer.
 99. A magnetic disk driveas claimed in claim 98 wherein each of the first film of the firstferromagnetic layer and the second film of the second ferromagneticlayer is cobalt iron niobium hafnium (CoFeNbHf).
 100. A magnetic diskdrive as claimed in claim 99 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 101. A magnetic disk drive as claimed in claim 84 wherein: theantiferromagnetic layer is selected from the group comprising nickelmanganese (NiMn), platinum manganese (PtMn) and iridium manganese(IrMn).
 102. A magnetic disk drive as claimed in claim 101 wherein saidat least one of said first and second ferromagnetic layers is cobaltiron niobium hafnium (CoFeNbHf).
 103. A magnetic disk drive as claimedin claim 102 wherein the second ferromagnetic layer is cobalt (Co). 104.A magnetic disk drive as claimed in claim 103 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 105. A magnetic disk drive as claimed inclaim 101 wherein: the first ferromagnetic layer includes first andsecond films, the first film being selected from said group and thesecond film being cobalt (Co) and being located between the first filmand the ruthenium (Ru) spacer layer; and the second ferromagnetic layerbeing cobalt (Co).
 106. A magnetic disk drive as claimed in claim 105wherein the first film is cobalt iron niobium hafnium (CoFeNbHf).
 107. Amagnetic disk drive as claimed in claim 106 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 108. A magnetic disk drive as claimed inclaim 101 wherein each of the first and second ferromagnetic layers isselected from the group.
 109. A magnetic disk drive as claimed in claim108 wherein each of the first and second films is cobalt iron niobiumhafnium (CoFeNbHf).
 110. A magnetic disk drive as claimed in claim 109including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 111. A magnetic diskdrive as claimed in claim 101 wherein: the first ferromagnetic layer hasfirst and second films and the second ferromagnetic layer has a firstfilm; each of the first films being selected from the group and thesecond film of the first ferromagnetic layer being cobalt (Co); and theruthenium (Ru) spacer layer having first and second surfaces with thefirst surface interfacing the second film of the first ferromagneticlayer and the second surface interfacing the first film of the secondferromagnetic layer.
 112. A magnetic disk drive as claimed in claim 111wherein each of the first films is cobalt iron niobium hafnium(CoFeNbHf).
 113. A magnetic disk drive as claimed in claim 112including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 114. A magnetic diskdrive as claimed in claim 101 wherein: each of the first and secondferromagnetic layers includes first and second films; the first film ofthe first ferromagnetic layer and the second film of the secondferromagnetic layer being selected from the group; the second film ofthe first ferromagnetic layer and the first film of the secondferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 115. A magnetic disk drive as claimed in claim 114 wherein eachof the first film of the first ferromagnetic layer and the second filmof the second ferromagnetic layer is cobalt iron niobium hafnium(CoFeNbHf).
 116. A magnetic disk drive as claimed in claim 115including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 117. A method of makinga combined read and write head that has an air bearing surface (ABS)comprising: a making of the read head including: forming a ferromagneticfirst shield layer; forming a nonmagnetic electrically insulative firstgap layer on the first shield layer; forming a spin valve sensor on thefirst gap layer as follows: forming a pinning layer that has magneticspins oriented in a first predetermined direction; forming anantiparallel (AP) pinned layer as follows: forming a first ferromagneticlayer on the pinning layer with a magnetic moment pinned parallel tosaid first predetermined direction; forming a film of ruthenium (Ru) onthe first ferromagnetic layer; forming a second ferromagnetic layer onthe ruthenium (Ru) layer that has a magnetic moment pinned in a secondpredetermined direction that is antiparallel to said first predetermineddirection; selecting at least one of the ferromagnetic layers from agroup comprising cobalt iron niobium hafnium (CoFeNbHf), cobalt ironniobium (CoFeNb, cobalt iron hafnium (CoNbHf); forming a nonmagneticelectrically conductive first spacer layer on the second ferromagneticlayer of the AP pinned layer; forming a ferromagnetic free layer on thefirst spacer layer that has a magnetic moment that is free to rotaterelative to the second predetermined direction of the AP pinned layer inresponse to an applied field; forming first and second electricallyconductive lead layers on the first gap layer that are connected to thesensor; forming a nonmagnetic electrically insulative second gap layeron the sensor, the lead layers and the first gap layer; and forming aferromagnetic second shield layer on the second gap layer; a making ofthe write head including: forming a write gap layer and an insulationstack with a coil layer embedded therein on the second shield layer sothat the second shield layer also functions as a first pole piece forthe write head; and forming a second pole piece layer on the insulationstack and the write gap and connected at a back gap to the first polepiece.
 118. A method as claimed in claim 117 including: the pinninglayer being nickel oxide (NiO); and an interface layer of nickel iron(NiFe) having first and second surfaces, the first surface beingexchange coupled to the pinning layer and the second surface beingexchange coupled to the pinned layer.
 119. A method as claimed in claim118 wherein said at least one of said first and second ferromagneticlayers is cobalt iron niobium hafnium (CoFeNbHf).
 120. A method asclaimed in claim 119 wherein the second ferromagnetic layer is cobalt(Co).
 121. A method as claimed in claim 120 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 122. A method as claimed in claim 118wherein: the first ferromagnetic layer includes first and second films,the first film being selected from said group and the second film beingcobalt (Co) and being located between the first film and the ruthenium(Ru) spacer layer; and the second ferromagnetic layer being cobalt (Co).123. A method as claimed in claim 122 wherein the first film is cobaltiron niobium hafnium (CoFeNbHf).
 124. A method as claimed in claim 123including: a giant magnetoresistive (GMR) enhancement layer of cobalt(Co); the GMR enhancement layer being located between the pinned andspacer layers and interfacing the spacer layer.
 125. A method as claimedin claim 118 wherein each of the first and second ferromagnetic layersis selected from the group.
 126. A method as claimed in claim 125wherein each of the first and second films is cobalt iron niobiumhafnium (CoFeNbHf).
 127. A method as claimed in claim 126 including: agiant magnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 128. A method as claimed in claim 118wherein: the first ferromagnetic layer has first and second films andthe second ferromagnetic layer has a first film; each of the first filmsbeing selected from the group and the second film of the firstferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 129. A method as claimed in claim 128 wherein each of the firstfilms is cobalt iron niobium hafnium (CoFeNbHf).
 130. A method asclaimed in claim 129 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 131. A method as claimed in claim 118 wherein: each of the firstand second ferromagnetic layers includes first and second films; thefirst film of the first ferromagnetic layer and the second film of thesecond ferromagnetic layer being selected from the group; the secondfilm of the first ferromagnetic layer and the first film of the secondferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 132. A method as claimed in claim 131 wherein each of the firstfilm of the first ferromagnetic layer and the second film of the secondferromagnetic layer is cobalt iron niobium hafnium (CoFeNbHf).
 133. Amethod as claimed in claim 132 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layersand interfacing the spacerlayer.
 134. A method as claimed in claim 117 wherein: theantiferromagnetic layer is selected from the group comprising nickelmanganese (NiMn), platinum manganese (PtMn) and iridium manganese(IrMn).
 135. A method as claimed in claim 134 wherein said at least oneof said first and second ferromagnetic layers is cobalt iron niobiumhafnium (CoFeNbHf).
 136. A method as claimed in claim 135 wherein thesecond ferromagnetic layer is cobalt (Co).
 137. A method as claimed inclaim 136 including: a giant magnetoresistive (GMR) enhancement layer ofcobalt (Co); the GMR enhancement layer being located between the pinnedand spacer layers and interfacing the spacer layer.
 138. A method asclaimed in claim 134 wherein: the first ferromagnetic layer includesfirst and second films, the first film being selected from said groupand the second film being cobalt (Co) and being located between thefirst film and the ruthenium (Ru) spacer layer; and the secondferromagnetic layer being cobalt (Co).
 139. A method as claimed in claim138 wherein the first film is cobalt iron niobium hafnium (CoFeNbHf).140. A method as claimed in claim 139 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 141. A method as claimed in claim 134wherein each of the first and second ferromagnetic layers is selectedfrom the group.
 142. A method as claimed in claim 141 wherein each ofthe first and second films is cobalt iron niobium hafnium (CoFeNbHf).143. A method as claimed in claim 142 including: a giantmagnetoresistive (GMR) enhancement layer of cobalt (Co); the GMRenhancement layer being located between the pinned and spacer layers andinterfacing the spacer layer.
 144. A method as claimed in claim 134wherein: the first ferromagnetic layer has first and second films andthe second ferromagnetic layer has a first film; each of the first filmsbeing selected from the group and the second film of the firstferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 145. A method as claimed in claim 144 wherein each of the firstfilms is cobalt iron niobium hafnium (CoFeNbHf).
 146. A method asclaimed in claim 145 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.
 147. A method as claimed in claim 134 wherein: each of the firstand second ferromagnetic layers includes first and second films; thefirst film of the first ferromagnetic layer and the second film of thesecond ferromagnetic layer being selected from the group; the secondfilm of the first ferromagnetic layer and the first film of the secondferromagnetic layer being cobalt (Co); and the ruthenium (Ru) spacerlayer having first and second surfaces with the first surfaceinterfacing the second film of the first ferromagnetic layer and thesecond surface interfacing the first film of the second ferromagneticlayer.
 148. A method as claimed in claim 147 wherein each of the firstfilm of the first ferromagnetic layer and the second film of the secondferromagnetic layer is cobalt iron niobium hafnium (CoFeNbHf).
 149. Amethod as claimed in claim 148 including: a giant magnetoresistive (GMR)enhancement layer of cobalt (Co); the GMR enhancement layer beinglocated between the pinned and spacer layers and interfacing the spacerlayer.